package com.seo.utils.code;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.QuadCurve2D;
import java.awt.image.BufferedImage;
import java.util.Random;

public class CaptchaUtils {

    public static final String    CODE_SESSION = "CODE_SESSION";

    public static final String    CODE_PROXY_USER_SESSION = "CODE_PROXY_USER_SESSION";
    
    // 默认的验证码大小
    private static final int      WIDTH        = 180, HEIGHT = 50;
    // 验证码随机字符数组
    protected static final char[] charArray    = "3456789ABCDEFGHJKMNPQRSTUVWXY".toCharArray();
    // 验证码字体
    private static final Font[]   RANDOM_FONT  = new Font[] { new Font("nyala", Font.BOLD, 30),
                                                              new Font("Arial", Font.BOLD, 32),
                                                              new Font("Bell MT", Font.BOLD, 30),
                                                              new Font("Credit valley", Font.BOLD,
                                                                  32),
                                                              new Font("Impact", Font.BOLD, 32),
                                                              new Font(Font.MONOSPACED, Font.BOLD,
                                                                  32) };

    /**
     * 生成验证码
     * 
     * @throws Exception
     */
    public static BufferedImage generate() throws Exception {
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

        return image;
    }

    public static String drawGraphic(BufferedImage image) {
        // 获取图形上下文
        Graphics2D g = image.createGraphics();

        g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
            RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
        // 图形抗锯齿
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        // 字体抗锯齿
        g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
            RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

        // 设定背景色，淡色
        g.setColor(getRandColor(210, 250));
        g.fillRect(0, 0, WIDTH, HEIGHT);

        // 生成随机类
        Random random = new Random();
        // 画小字符背景
        Color color = null;
        for (int i = 0; i < 20; i++) {
            color = getRandColor(120, 200);
            g.setColor(color);
            String rand = String.valueOf(charArray[random.nextInt(charArray.length)]);
            g.drawString(rand, random.nextInt(WIDTH), random.nextInt(HEIGHT));
            color = null;
        }
        // 取随机产生的认证码(4位数字)
        String sRand = "";
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(charArray[random.nextInt(charArray.length)]);
            sRand += rand;
            // 旋转度数 最好小于45度
            int degree = random.nextInt(28);
            if (i % 2 == 0) {
                degree = degree * (-1);
            }
            // 定义坐标
            int x = 44 * i, y = 25;
            // 旋转区域
            g.rotate(Math.toRadians(degree), x, y);
            // 设定字体颜色
            color = getRandColor(20, 130);
            g.setColor(color);
            // 设定字体，每次随机
            g.setFont(RANDOM_FONT[random.nextInt(RANDOM_FONT.length)]);
            // 将认证码显示到图象中
            g.drawString(rand, x + 8, y + 10);
            // 旋转之后，必须旋转回来
            g.rotate(-Math.toRadians(degree), x, y);
        }
        // 图片中间曲线，使用上面缓存的color
        g.setColor(color);
        // width是线宽,float型
        BasicStroke bs = new BasicStroke(3);
        g.setStroke(bs);
        // 画出曲线
        QuadCurve2D.Double curve = new QuadCurve2D.Double(0d, random.nextInt(HEIGHT - 8) + 4,
            WIDTH / 2, HEIGHT / 2, WIDTH, random.nextInt(HEIGHT - 8) + 4);
        g.draw(curve);
        // 销毁图像
        g.dispose();
        return sRand;
    }

    /**
     * 给定范围获得随机颜色
     */
    private static Color getRandColor(int fc, int bc) {
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
}
